Plugboards for patchcord systems



May 3l, 1960 W. s. WATTS 2,939,100

PLUGBOARDS FOR PATCHCORD SYSTEMS Filed Nov. 2, 1955 2 Sheets-Sheet l mmv/ia@ Z/v/zamf INVEN TOR.

Mmmm flhfdtt BY M. 24W

May 31, 1960 w. s. WATTS 2,939,100

PLUGBOARDS FOR PATCHCORD SYSTEMS Filed Nov. 2, 1955 2 sheets-sheet 2 INVENTOR 60' Mmmm 5- Ufais M.WVW

United States Patent C) PLUGBoAnns non PA'rcHcoRn SYSTEMS William S. Watts, Harrisburg, Pa., assigner to AMI Incorporated, Harrisburg, Pa.

Filed Nov. 2, 1955, Ser. No. 544,467

7 Claims. (Cl. 339-18) This invention relates to patchcord systems utilized in connection with electrical accounting or computing machines or the like, and more particularly to the plug or contact boards of such systems.

lt has become customary to install the control functions of such machines in a patchcord control system that conventionally includes a pair of contact or plug boards that carry the rows and columns of electrical contacts to be interconnected in a variable predetermined arrangement according to the manner in which the control components of the machine are to be operated. The contactcarrying boards, one of which is usually fixed relative to the machine while the other is moved into and out'of cooperating relationship therewith, are positioned in and relatively manipulated by suitable mechanism as shown, for example, in the application, Serial No. 411,969, filed February 23, 1954.

The rows and columns of contact elements on oneV board typically constitute the terminals of electrical conductors leading from the sensing elements and the instrumentalities to be controlled in the machine, and on the other board provide rearrangeable interconnecting plugs or jacks through which the particular circuit connections on the first board may be made. In an average system, several hundred contact elements are located on each board in a minimum area with a minimum space between rows and columns. As a result, where the board is formed from insulating material current leakage can occur between contacts producing a more or less detri-l mental eiect on the operation of the machine according to its character. For example, in an analog computer information is generally represented by voltage pulses or levels which are compared for resolution to a xed reference level on a relative magnitude basis. Any signicant leakage between contacts on the plugboard at theV control station introduces an error function in the handling of the information which should be avoided. This current leakage, in contact boards as heretofore designed, may appear either as volume leakage through the body of the insulating or plastic material, or as surface leakage between the contacts and becomes more signicant a factor should there be any aws or imperfections within the molded structure of the board or upon accumulation of any lm or foreign matter on the surface of the board.

One solution that has been proposed to shield the contacts in the patchcord control system against current leakage has been to form the boards of a conductive metallic material, such as aluminum, and providing insulation sleeves for the contact elements within the board apertures. Such an arrangement is disadvantageous, however, in that it is desirable to permit rearrangement of the electrical connections while the plugboards are interconnected and the contacts energized. With a metal board structure there then arises the danger, in making the change or rearrangement desired in the connections, of accidently grounding an energized plug or jack through the board with a possible result of damage to the elec- 2,939,100 Patented May 31, 1960 ICC trical elements of the computer or machine and the ntroduction of erroneous information into the system controlled by the patchcord system.

Accordingly, it is an object of the present invention to provide in a patchcord system an improved shielded contact board construction.

Another object is to provide in a patchcord system an improved construction for shielded contact boards which eliminates the possibility of grounding energized contacts during rearrangement of the electrical connections afforded by the system.

Still another object is to provide in a patchcord system an improved shielded contact board which is simple in construction and facile to manufacture.

A further object is to provide for a patchcord sys-A tem a prefabricated contact board employing a minimumA is to be understood, however, that these embodiments' are not intended to be exhaustive nor limiting of theV invention but are given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

Figure l is a perspective view of one embodiment of the contact board with certain parts being broken away to illustrate some of the details of construction;

Figure 2 is a fragmentary perspective view illustrating the method of assembly of the parts comprising the contact board shown in Figure l;

Figure 3 is a sectional view taken along lines 3-3 of Figure l;

Figure 4 is a perspective view of an insert or bushing utilized in forming the contact board of Figure l;

I Figure 5 is a sectional side view of the insert or bush- .l lng of Figure 4 illustrating the cooperation therewith of' a plug or jack contact element employed within the patchcord system;

Figure 6 is a perspective view of another embodiment with certain parts being broken away to illustrate details of construction;

Figure 7 is a sectional view taken along lines `77 of Figure 6; f

Figure 8 is a fragmentary perspective view of another embodiment of the contact board with certain parts being broken away to illustrate details of construction;

Figure 9 is a sectional view taken along lines 9-9 of Figure 8; and

Figure 10 is a fragmentary perspective View showing Y one of the boards is xed in position inthe patchcord.'l system atthe control station of the machine or device.

involved, the other board being detachably slidably mounted in a carrier frame'which is manipulated by the control mechanism of the patchcord system. In either event it is to be understood that the principles of the,v applied in the construction of A present invention may be the patchcord system.

between vthe contacts is'prev'entedr due With reference to theY embodiment shown in Figure 1, the contact board 2 typically is of rectangular configuration and has a plurality of rows and columns of apertures V4 extending therethrough for rigidly supporting in closely spaced relationship the contact elements, such' as the spring and plug contacts described in the respective applications, Serial No. 409,603, filed February l1, 1954, now Patent No. 2,882,508 issued April 14, 1959 to William S. Watts, and Serial No. 418,413, tiled March 24, 1954, now Patent No. 2,903,670, issued" September 8, 1959, to'Gilbert C. Sitz. To provide for shielding and to prevent intercontact leakage while retaining the advantages inherent in a board of insulating'materiaLreach of the contact-receiving. apertures 4 Yis formed in' an in# dividual/ block or bushing 6 of insulating material, such as nylon, which is disposed in electrical isolation fromadjacent blocks within a pocket or section 8 of an' electrically conductive grid, generallyY designated atYV 10, of any suitable metallic material'.

As best shown in Figures 2 and 3, grid 10 is composed of a plurality of elongated at strips 12 interconnected and arranged to present thin side faces 14 at the front and rear surfaces A and B of the board'. The major width of strips 12 approximates the length and thus effectively shields the side faces of bushings 6 Whichdene the contact board thickness; SurfacesV A and AB of board 2 is a composite of the end faces of insulating bushings 6 and strip side faces 14, the conductive surfaces ofY which preferably are inaccessible to engagement by the contact elements of the system as will be explained.

It will be understood by those skilled inthe art that metallic grid and insulating blocks or bushings 6 may takeY avariety of forms in cooperating to provide the.

rigid contact yboard 2. For example, acomposite molded structure will suiice. 'I 'o lend Versatility in the manufacture of the board, however, it is preferred that grid 10-be formed from strips, each having a series of equally spaced slots 16 transversely extending one-half the strip` width from a side face 14, which thus may be interm'eshed in a series of halved lapjoints' at the grid crossover points, Figure 2. .To secure thev grid joints and the bushings withinrthe grid, each bushing is provided at opposite ends with transverse lips or'flanges 18 and 20, iiange 18projecting from two side faces of the generally hexadhedral body of the bushing and flange 20 from the opposite side faces, Figure 4. The widthY of stripsV 12 should then be equal to the length of bushings 6 between4 flanges 18 and 20 so that upon assembly of the parts, of l the' four stripsl forming each pocket 8, ange 18 will overlie the side face 14 of two adjacent strips on one face of the-board while flange 20 engagesv the side faces ofthe remaining 'pair of strips on the thereby locking both the grid joints and bushings in position. A frame 22 provided with grooves 24 for receiving the extremities 26 of strips 12 serves to'maintain the" rigidity of the contact board structure, the frame being suitably held together as by bolts 2 8.

To stabilize the position of the contact elements within the'board the body of bushings 6 in cross-section should precisely t the area of associated pocketsr 8. To take upV design tolerances and to assure the desired snug lit` bushings 6 are provided with a pair of resiliently deformable longitudinal ribs 30 which are compressedaccording to the relative differences in cross-sectionalareas of the bushing and grid openings.

Where the contact board supports the plug elementsl ofthe system each bushing may be provided with adetent 32 extending inwardly'at' one end of aperturek 4 that cooperatesrwith an annular groove 34 of the plug to 70 secure the plugin positionas shown in VFigure 5. u A

rAs thus' constructed volume leakage through the board to the interpositon ofthe conductive strips 12. to surface leakage, it is contemplated that flangesi'lS and 20 of onelbushing do not project so far as to abut the sideso adjacent'bshl opposite face of thekboarcl 4 ings, but vdet'nea series'o'f narrow grooves 36 leaving portions of the contiguous strips? 12 at side faces 14 exposed, thereby providing with respect to surface leakage a low resistance path of conductive metal surrounding each of the contact elements on both surfaces A and B of the board. The space between adjacent bushings should not be so larger, however, as to permit engagement of the conductive strips by the contact elements of the system. For example, the Width of Ygrooves 36 should be less in dimensions than'nose 38 of the' contact plug thus preventing accidental grounding of the contact element during insertion thereof in the board. It is to be understood, of course, that all of the conductive strips 12 are in electrical contact and in contact With'the metallic frame 22 which may be grounded through the contact board carrying frame, shown in dotted lines 40 in Figure 3, of the Ypatchcord system. Similarly, carrying frame 40 Vmay tial. In general, however, it will be understood that with vappropriate connections frame 22, together with conductive strips 12, may be maintained at any desired potential thereby to provide a variable reference voltage level forthe contact elements.

'Ihe maximum number of contacts in any board will, of course, depend upon the characteristics of a particular use. Commonly, however, the variations in the number of contacts is a multiple of the smallest board desired. In the manufacture of the board, therefore, stripse1`2 may be formed as long as is required of the largest board contemplated to be produced. For smaller boardl sizes, the strips may simply be cut to length which, with standardized bushings, thus permits the prefabrication ofV anysized board Without waste of material.

Where the conditions of a, particular use require ai* shielding of thecontact elements only as to either surface or to volume leakage, the contact board may take either of the simplified forms shown respectively in Figures 6 and 7 or Figures 8 and 9. In the embodiment of Figures 6 and 7 the base 42 of contactV board 44`is ofinsuto ground through carrier frame 52 for leakage currents between ,the contact elements4 on the board surfaces. Similarly, in theembodiment shown in Figures 8 and 9,V a conductive sheet 54 suitably disposedwithin the body of insulating base 56 provides a low resistance path to groundy through contact with the carrier frame at edges 58Vfor leakage Ycurrents between contacts through the body of the insulating material.

Any method, such as molding processes well-known Y in the art, for forming the contact boards of Figures 6 and 7 will suffice. In the event a molded construction is preferred, contactvplates 46 andV 54 may be rigidwrnembers directly Vmolded with thebasematerial, or if desired, may Ybe thin sheets of metal foil laminated Vto the base by bonding techniques conventional in the art. Out- Wardly'p'rojectingY lugs 60 may be provided to assure in the molding operation a secure interlocking between the insulating base and conductive sheets.

`I claim: j

l. A multiple-contact boardY for a patchcord system comprising" an electrically conductive grid, insulation means within' the interstices of said grid to form therewith the body ofsaid board, said insulation-means extendingpartially over the conductive surfaces presented* by said' grid on' at least onefa'ceof said board and havingj .apertures therein for' receiving' the contact elements of thesystem, and said apertures being. substantiallyk cen` teredwit'hin said linterstices respectively.

2. A multiple-contact board for a patchcord system comprising a plurality of conductive strips assembled in the form of a grid, a plurality of bushings of insulating material tting within the interstices of said grid to form therewith the body of said board, flange means on said bushings adapted to overhang the side edges of the respective contiguous portions of said strips for reducing the width of the conductive surface presented by said side edges on one face of the board, and apertures in said bushings for receiving the contact elements of the system.

3. A multiple-contact board for a patchcord system comprising a plurality of conductive strips assembled in the form of a grid, a plurality of bushings of insulating material fitting within the interstices of said grid to form therewith the body of said board, flange means on the ends of said bushings extending partially over the conductive surfaces presented by said grid on opposed faces of the board for locking the bushings within the grid, and apertures in said bushings for receiving the contact elements of the System.

4. A multiple-contact board for a patchcord system comprising a plurality of similar conductive strips, each having a series of spaced slots extending laterally from one side edge assembled in a lapped-joint grid arrangement, a plurality of bushings of insulating material tting within the interstices of said grid to form therewith the body of said board, apertures in said bushings for receiving the contact elements of the system, and means for securing said strips and bushings in assembled relationship.

5. A multiple-contact board for a patchcord system comprising a plurality of similar conductive strips, each having a series of regularly spaced slots extending laterally from one side edge substantially one-half the strip width assembled into a grid having halved lap joints at the crossover points, a plurality of bushings of insulating material fitting within the interstices of said grid to form therewith the body of said board, complementary ange means on one end of said bushings adapted to overhang the side edges of the respective contiguous portions of said strips for reducing the width of the conductive surface presented by said Side edges on one face of the board, ange means on the other end of said bushings for cooperating with said complementary ange means to lock said bushings within the grid and the grid joints in assembled relationship, apertures in said bushings for receiving the contact elements of the system, and a frame for receiving the end portions of said strips.

6. A multiple-contact board for a patchcord system comprising insulation means having a plurality of aper tures therein extending through said board for receiving.

the contact elements of the system, and conductive metallic means spaced from the sidewalls of said insulation means defining said apertures and surrounding said apertures, said metallic means extending continuously through the thickness of said board for providing an electrical shield between contact elements in adjacent apertures.

7. A multiple contact board for a patchcord system comprising a plurality of conductive strips assembled in the form of a grid, a plurality of bushings of insulating material fitting within the interstices of said grid to form therewith the body of said board, said bushings having resiliently deformable means thereon adapted resiliently to engage said strips to eiect a tight fit of said bushings within said interstices, and apertures in said bushings for receiving the contact elements of the system.

References Cited in the le of this patent UNITED STATES PATENTS 2,006,436 Bowers July 2, 1935 2,133,254 Nelson Oct. 11, 1938 2,714,195 Beatty July 26, 1955 

